The Himeji LCD factory we visited the another day may have been very new, and therefore not quite set up for visitors yet, but things are more established along the coast at Amagasaki. We're closer to Osaka now, and at the heart of Panasonic's plasma display business.

The three factories, on another coastal site with an expressway spearing overhead between the facilities, are actually Panasonic Plasma 3, 4, and 5, and they form the world's largest plasma display panel manufacturing facility.

Two earlier facilities are elsewhere in the Osaka area, and while P4 is running at full capacity, turning out some 600,000 PDP panels a month, and P3 a further 340,000, P5 was only started in June 2009, and is still not at full production, although it is mass-producing some of the company's largest screens. The company also makes panels in China, near Shanghai.

With each new factory, Panasonic is able to handle larger sheets of motherless, and make further efficiencies in the production process: P4 uses what the company calls 8-cut glass and others describe as eighth-generation, producing eight 42in panels from a single sheet, while P5 runs massive 16-cut sheets, yielding twice as many screens per sheet.

Panasonic says P5 is a Generation 10.5 facility: "Well, Sharp built its new factory at Sakai – not so far away – and called it 10th-generation. It gets 15 panels from a sheet of glass, so of course Panasonic, with one more panel per sheet, must be 10.5!'

And the larger sheets cut process time and costs – well, once you've factored in the eyewatering cost of building one of these facilities and kitting it out with all the equipment needed to handle the huge sheets of glass and finish them. Compared with the company's original plasma factory processing time is down 23% at P4, and 33% at P5, and production lead times are also cut: P5 can respond to changes in demand for panels almost twice as fast as could P1.

The company's striving for more eco-friendly production is also much in evidence here: a photocatalytic coating on the walls breaks down Nitrous Oxide in the air, preventing pollution, there's extensive recycling of everything from production waste to water, and even the huge corporate logos high on the walls are lit with LEDs, not neon.

Completing the picture, the trucks used to transport materials and finished goods run on natural gas, not diesel, greatly reducing carbon dioxide and nitrous oxide emissions.

The plasma production process at Amagasaki

Panasonic's Shinji Inoue – we met him at the Himeji plant, remember? – explains that while several thousand people work here, across round the clock shifts, the high level of automation and extensive clean room working means that, to the casual eye, it can be hard to spot any workers at all.

In an observation room high above the main coating and patterning facility, we peered through the yellow-tinted windows – the process is photographic, so lighting is as controlled as the atmosphere – looking for what Inoue called the 'white ninjas': staff dressed in their clean suits, masks and hoods, with only their eyes visible through a narrow slit.

I thought I caught a fleeting glimpse of someone between the ranks of glass-sided machines, but before I could ask, they'd vanished again. Maybe just imagination?

Very real are the huge robots, all elegant movements, clicking machinery and hissing air-valves, that take the incoming glass from its vertical pallet, remove the paper interleaved between the sheets, swish it through the air like samurai battle-flags before depositing it in a recycling bin, then go back for the glass and place it on a roller system to enter the processing plant.

Part aerial ballet, part vaguely menacing as they seem to pause and consider their next move, the robots had all of our tour-group intrigued.

And we were jaw-dropped by the 100m-long ovens in which the glass panels for the display are sealed together once they have been assembled. The panels, stacked in metal racks, run slowly through the ovens as temperature is built up to 400C and then reduced again over a nine-hour period.

If you were thinking of setting up your own plasma panel plant – as some of our group seemed to be, so liberally were they scattering insights of advice on how things should be done to the experts who do this day in, day out – a used oven from your local pizza takeaway isn't going to be up to the job.

Finally, we got to have a look at the company's flagship 152in 3D 4K2K plasma, and very impressive it looked too, showing some of the kind of ultra high resolution detailed images often used for such demonstrations.

I was less sold when watching an excerpt from Dances with Smurfs on the big screen: the effect is certainly cinematic, but I was getting some juddering of motion, not to mention the irritation of the portentous music and impossible dialogue. Judging from the gasps of delight from my fellow hacks, however, it may just have been me…

By the way, if you need to ask, the 152in screen is around €500,000, depending on the installation. They can only airship one at a time in the cargo hold of a 747, so big is the screen, and they build them to order. None of which has stopped a Middle Eastern customer buying eight: one for himself, three for the wives, and the rest for assorted relatives.

More exciting was a prototype plasma TV just 8mm thick, on display in the same room as the monster screen. It looked sexy and really rather desirable – though apparently not sufficiently so to stop questions about OLED screens to come up on average once an hour throughout the trip.

Answer? Not yet, too expensive and too small to be viable for a good while.

Other good questions at Amagasaki? How many litres of water does it take to make a plasma screen, will they be making a 4K2K touchscreen you can use as a video pinboard, will they be making even smaller plasmas, and –

Oo! Ooo!! Look! White ninja...

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